The local_irq_disable() function and co. merely raise the interrupt mask on theMN10300 arch to exclude normal interrupts. This still lets other, higherpriority maskable interrupts through, such as are used to service gdbstub'sserial port and the MN10300 on-chip serial port virtual FIFOs.

Provide functions to allow the maskable interrupts to be fully disabled, whichwill exclude those interrupts.